To some extent all plants and animals try to defend themselves against attack. Nothing likes to be eaten. In animals, you get the all-to-obvious tooth and claw with which to fight off predators. Plants can also go for the thorn approach, but the more common approach is poison with a variety of different delivery systems. For the most part, humans need not worry about plants. Unless innocent children start eating berries, people are not going to be troubled. Except. . . except for the increasingly common poison ivy, poison oak and sumac. Starting with the ivy, this is not properly part of the ivy family. Rather it belongs to the group of vines producing cashew nuts and mangos. Like the other two dangerous plants, this produces a natural defense through its sap. Called urushiol, it produces a rash. If there is only a slight contact, this does no more than itch. But if the contact is more direct, the skin can blister and swell. Thanks to global warming, the ivy now spreads throughout most of North America, usually preferring wooded surroundings although, in urban areas, it grows along shaded hedge rows. Rather than ground cover, poison oak is a free-standing shrub and it’s to be found throughout the southeastern states, again mainly in forests and wooded areas. The final sumac is a big shrub or small tree growing up to about 20 feet in height in swampy conditions in eastern North America.
In many ways, it’s remarkable we accept the presence of so many poisonous plants in our towns, cities and surrounding countryside. Thousands of people are affected every year. It takes only the slightest touch for the reaction to come. If you know the contact has taken place, you should immediately wash the affected area with ordinary soap and water. Under normal circumstances, washing within five minutes of contact will prevent any significant rash forming. In other cases of mild contact, you will be able to control the resulting irritation and itching using calamine lotion. Cooling the skin also helps, so taking cold showers or using a compress usually reduces the annoying symptoms. Because this is an allergic reaction, taking one of the over-the-counter antihistamines will also help. If you do so, remember to buy one which does not make you drowsy. (more…)